The present invention relates to a blowing apparatus.
In recent years, with downsizing and electronizing tendencies of equipment, electrical circuits are frequently equipped at high densities. With such tendencies, since exothermic densities of electronic equipment are also increased, a blowing apparatus for cooling the equipment is used.
As shown in FIG. 3, a conventional blowing apparatus comprises a permanent magnet motor 3. The motor 3 includes a stator 1 having salient poles 1a including armature windings and a rotor 2 having permanent magnets 2a magnetized to a plurality of poles. The motor 3 drives a fan 4 having a plurality of blades 4a. A housing 5 is disposed around an outer periphery of the fan 4. The motor and the housing are fixed by means of a plurality of spokes 6.
However, when the stator core is worked, magnetic characteristics of the silent poles of the stator core differ due to deviation of working distortion or composition of the magnetic materials, and due to this distortion, even if the position of the silent poles of the stator and the magnetic poles of the rotor, and the conductive state are stable, a difference in generated torque is generated depending upon the silent poles. Such variation in torque generated by the distortion of the stator is caused the same times as the number of rotor poles with respect to the rotation of the rotor. This variation in torque acts as a vibration source and generates vibration and noise. Further, when the fan is rotated, vibrations are generated the same times as the number of fan blades per one rotation. Here, if the rotation frequency is defined as 1-degree, and the number of vibration of the variation per one rotation of the rotor is defined as order, if the same number of blades as the order or a submultiple of vibration generated due to the stator distortion or twice the number of blades are mounted, vibration generated by stator distortion and vibration generated by the rotation of blades coincide with each other, and there is a problem that the vibration is increased. Thereupon, in the conventional technique, the number of rotor poles is 4 and the number of fan blades is 6 and thus, the basic order of vibration is 12th-degree which is a minimum common multiple of 4 and 6.
Further, in the rotor portion, depending upon mechanical distortion of a rotor frame and permanent magnet, polarization distortion of the permanent magnet, deviation caused by assembling distortion of a shaft and a bearing, effective magnetic flux amount crossing the stator winding from the rotor permanent magnet differs. That is, since the generated torque is different depending upon magnetic poles, this is a cause of vibration which generates distortion of rotation. The vibration caused by the rotor distortion is generated the same times as the number of stator silent poles with respect to the rotor rotation. If the same number of blades as the order or a submultiple of vibration generated due to the rotor distortion or twice the number of blades are mounted, vibration generated by stator distortion and vibration generated by the rotation of blades coincide with each other, and there is a problem that the vibration is increased. Thereupon, in the conventional technique, the number of rotor poles is 4 and the number of fan blades is 6 and thus, the basic order of vibration is 12th-degree which is a minimum common multiple of 4 and 6.
Further, in the permanent magnet motor, magnetic flux generated from the permanent magnet crosses the stator core. Since the stator core has a shape of the silent pole, the magnetic resistance is varied by the rotational position of the rotor and thus, torque called cogging torque which is proportional to variation ratio of the magnetic resistance is generated in the rotor. The cogging torque is varied depending upon the positional relation between the silent pole of the stator core and the rotor magnetic pole, and variation is generated in the minimum common multiple of the number of stator silent poles and the number of rotor magnetic poles with respect to the rotor rotation, and this causes vibration of the motor. If the same number of blades as the order or a submultiple of vibration generated due to the rotor distortion or twice the number of blades are mounted, vibration generated by stator distortion and vibration generated by the rotation of blades coincide with each other, and there is a problem that the vibration is increased. Thereupon, in the conventional technique, the number of stator silent poles is 4, the number of rotor magnetic poles is 4 and the number of fan blades is 6, the basic order of the cogging torque is 4 th-degree which is a minimum common multiple of the number of stator silent poles and the number of rotor magnetic poles, and the basic order of vibration is 12th-degree which is a minimum common multiple of 4 and 6.
In the blowing apparatus, the motor to which the fan is mounted is fixed to the housing through the spokes. Vibration generated by the motor and the fan is transmitted to the spokes and the housing. Therefore, shapes of the spokes and housing largely effect the vibration of the blowing apparatus.
As a method for reducing the vibration of the blowing apparatus, there is a method to reduce the cogging torque which is a source of vibration, and to optimize the shapes of various members, but even if the vibration source of the motor and the fan is reduced, vibration of the entire blowing apparatus is not reduced depending upon the combination in some cases.
The present invention is for solving the conventional problem, and it is an object of the invention to provide a blowing apparatus having low noise and vibration.
To solve the above problem, the present invention proposes a blowing apparatus comprising a stator having a core including a M-number of salient poles, a rotor having permanent magnets having a P-number of magnetic poles rotatably disposed such as to be opposed to magnetic pole surfaces of the stator, a motor for rotating a fan having a N-number of blades, a polygonal housing having a Q-number of sides disposed around an outer periphery of the fan, and a R-number of spokes for fixing the housing and the motor. The minimum common multiple is increased by various combinations of the numbers.
With the above means, it is possible to increase the order of vibration, i.e., it is possible to reduce the energy of vibration and to suppress the vibration and noise of the blowing apparatus. When the above blowing apparatus is mounted in a apparatus. When the above blowing apparatus is mounted in a personal computer as electronic equipment for example, it is possible to reduce the noise of the electronic equipment.
To solve the above problem, the present invention provides a blowing apparatus comprising a stator having a core including a M-number of salient poles, a rotor having permanent magnets having a P-number of magnetic poles rotatably disposed such as to be opposed to magnetic pole surfaces of the stator, the stator and the rotor, in combination, forming a motor for rotating a fan having a N-number of blades, a polygonal housing having a Q-number of sides disposed around an outer periphery of the fan, and a R-number of spokes for fixing the housing and the motor, wherein mNxe2x89xa0nM is satisfied.
The present invention satisfies mNxe2x89xa0nP.
If a minimum common multiple of the number M of the stator salient poles and the number P of rotor magnetic poles is defined as A, the invention satisfies mNxe2x89xa0nA.
Further, the invention satisfies mQxe2x89xa0nM.
Further, the invention satisfies mQxe2x89xa0nP.
Further, the invention satisfies mQxe2x89xa0nA.
Further, the invention satisfies mQxe2x89xa0nN.
Further, the invention satisfies mRxe2x89xa0nM.
Further, the invention satisfies mRxe2x89xa0nP.
Further, the invention satisfies mRxe2x89xa0nA.
Further, the invention satisfies mRxe2x89xa0nN.
Further, the invention satisfies mRxe2x89xa0nQ.
The present invention provides electronic equipment incorporating the above blowing apparatus.
Here, one of m and n is a natural number which is a factor with respect to the other.
According to the blowing apparatus having the above structure, it is possible to suppress the noise and vibration. More specifically, the invention has the following effect.
According to a first aspect of the invention, by selecting the number M of the stator salient poles and the number N of the fan blades such that the number M of the stator salient poles does not become a multiple of the number N of the fan blades and the number N of the fan blades does not become a multiple of the number M of the stator salient poles, it is possible to prevent an order vibration due to distortion or eccentricity of the rotor and an order of vibration due to the fan blades from coinciding with reach other, thereby increasing the order of the vibration of the fan. With the above arrangement, it is possible to suppress both the vibration generated by the distortion or eccentricity of the rotor and the vibration generated by the fan blades.
According to a second aspect of the invention, by selecting the number P of rotor magnetic poles and the number N of the fan blades such that the number P of rotor magnetic poles does not become a multiple of the number N of the fan blades and the number N of the fan blades does not become a multiple of the number P of rotor magnetic poles, it is possible to prevent an order vibration due to distortion of the stator and an order of vibration due to the fan blades from coinciding with reach other, thereby increasing the order of the vibration of the fan. With the above arrangement, it is possible to suppress both the vibration generated by the distortion of the stator and the vibration generated by the fan blades.
According to a third aspect of the invention, by selecting the number M of the stator salient poles, the number P of rotor magnetic poles and the number N of the fan blades such that the order A of the cogging torque does not become a multiple of the number N of the fan blades and the number N of the fan blades does not become a multiple of the order A of the cogging torque, it is possible to prevent a vibration due to the cogging torque and an order of vibration due to the fan blades from coinciding with reach other, thereby increasing the order of the vibration of the fan. With the above arrangement, it is possible to suppress both the vibration generated by the cogging torque which is peculiar to a permanent magnet motor and the vibration generated by the fan blades.
According to a fourth aspect of the invention, by selecting the number M of the stator salient poles and the number Q of sides of the housing such that the number M of the stator salient poles does not become the number Q of sides of the housing and such the number Q of sides of the housing does not become the number M of the stator salient poles, it is possible to prevent a vibration due to the distortion and eccentricity of the rotor and the vibration due to the housing from coinciding with reach other, thereby increasing the order of the vibration of the blowing apparatus. With the above arrangement, it is possible to suppress both the vibration generated by the distortion and eccentricity of the rotor and the vibration generated by the housing.
According to a fifth aspect of the invention, by selecting the number P of rotor magnetic poles and the number Q of side of the housing such that the number P of rotor magnetic poles does not become a multiple of the number Q of side of the housing and the number Q of side of the housing does not become a multiple of the number P of rotor magnetic poles, it is possible to prevent an order vibration due to distortion of the stator and an order of vibration due to the housing from coinciding with reach other, thereby increasing the order of the vibration of the blowing apparatus. With the above arrangement, it is possible to suppress both the vibration generated by the distortion of the stator and the vibration generated by the housing.
According to a sixth aspect of the invention, by selecting the number M of the stator salient poles, the number P of rotor magnetic poles and the number Q of side of the housing such that the order A of the cogging torque does not become a multiple of the number Q of side of the housing and the number Q of side of the housing does not become a multiple of the order A of the cogging torque, it is possible to prevent a vibration due to the cogging torque and an order of vibration due to the housing from coinciding with reach other, thereby increasing the order of the vibration of the blowing apparatus. With the above arrangement, it is possible to suppress both the vibration generated by the cogging torque which is peculiar to a permanent magnet motor and the vibration generated by the housing.
According to a seventh aspect of the invention, by selecting the number N of the fan blades and the number Q of sides of the housing such that the number N of fan blades does not become a multiple of the number Q of side of the housing and the number Q of side of the housing does not become a multiple of the number N of fan blades, it is possible to prevent an order vibration due to distortion of the fan and an order of vibration due to the housing from coinciding with reach other, thereby increasing the order of the vibration of the blowing apparatus. With the above arrangement, it is possible to suppress both the vibration generated by the fan blades and the vibration generated by the housing.
According to an eighth aspect of the invention, by selecting the number M of the stator salient poles and the number R of spokes such that the number M of the stator salient poles does not become a multiple of the number R of spokes and the number R of spokes does not become a multiple of the number M of the stator salient poles, it is possible to prevent an order vibration due to distortion or eccentricity of the rotor and an order of vibration due to the spokes from coinciding with reach other, thereby increasing the order of the vibration of the blowing apparatus. With the above arrangement, it is possible to suppress both the vibration generated by the distortion or eccentricity of the rotor and the vibration generated by the spokes.
According to a ninth aspect of the invention, by selecting the number P of rotor magnetic poles and the number R of spokes such that the number P of rotor magnetic poles does not become a multiple of the number R of spokes and the number R of spokes does not become a multiple of the number P of rotor magnetic poles, it is possible to prevent an order vibration due to distortion or eccentricity of the rotor and an order of vibration due to the spokes from coinciding with reach other, thereby increasing the order of the vibration of the blowing apparatus. With the above arrangement, it is possible to suppress both the vibration generated by the distortion or eccentricity of the rotor and the vibration generated by the spokes.
According to a tenth aspect of the invention, by selecting the number M of the stator salient poles, the number P of rotor magnetic poles and the number R of spokes such that the order A of the cogging torque does not become a multiple of the number R of spokes and the number R of spokes does not become a multiple of the order A of the cogging torque, it is possible to prevent a vibration due to the cogging torque and an order of vibration due to the spokes from coinciding with reach other, thereby increasing the order of the vibration of the blowing apparatus. With the above arrangement, it is possible to suppress both the vibration generated by the cogging torque which is peculiar to a permanent magnet motor and the vibration generated by the spokes.
According to an eleventh aspect of the invention, by selecting the number N of the fan blades and the number R of sides of the spokes such that the number N of fan blades does not become a multiple of the number R of spokes and the number R of spokes does not become a multiple of the number N of fan blades, it is possible to prevent an order vibration due to distortion of the fan and an order of vibration due to the spokes from coinciding with reach other, thereby increasing the order of the vibration of the blowing apparatus. With the above arrangement, it is possible to suppress both the vibration generated by the fan blades and the vibration generated by the spokes.
According to a twelfth aspect of the invention, by selecting the number R of spokes and the number Q of side of the housing such that the number R of spokes does not become a multiple of the number Q of side of the housing and the number Q of side of the housing does not become a multiple of the number R of spokes, it is possible to prevent an order vibration due to distortion of the stator and an order of vibration due to the housing from coinciding with reach other, thereby increasing the order of the vibration of the blowing apparatus. With the above arrangement, it is possible to suppress both the vibration generated by the distortion of the stator and the vibration generated by the housing.
According to a thirteenth aspect of the invention, vibration and noise of the electronic equipment are reduced.